I was wondering if the situation the OP is encountering is due to the SE tax.
Even after a large "proposed" extra 401k contribution, his tax only went down $1000. IF he had that much profit from his business to make such a large contribution, his SE tax would remain and be a substantial amount, even if his personal income tax was reduced to a zero. Yes?
Thus check line 22 of the 1040 before doing the proposed extra contribution, to see what regular income tax remains to be reduced. (if I have my line numbers right)
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
